1. Field of the Invention
The present invention relates to a vehicle headlamp and more particularly to a reflector-movable headlamp in which a reflector that has a light source is mounted is supported by an aiming mechanism so as to be tiltably moved with respect to a lamp body.
2. Prior Art
In a typical reflector-movable headlamp, a crown gear is provided at a rearward-extending portion of an aiming screw which is an aiming mechanism component and extends through a rear wall of the lamp body. With a screwdriver, the crown gear is rotated, thus rotatably operating the aiming screw.
One example of a headlamp of this type is disclosed in U.S. Pat. No. 5,647,659.
In this headlamp, as seen from FIG. 8, a reflector 2 housed in a lamp body 1 is supported by an aiming screw 3, which is the aiming mechanism component. The aiming screw 3 is rotatably supported by the rear wall of the lamp body 1, and a rotational operation bar 4 that extends upward along the rear wall is provided. An orthogonal conversion gear mechanism 5 composed of a plurality of gears is provided between the rotational operation bar 4 and a rear end portion of the screw 3 that protrudes rearward from the rear wall of the lamp body 1. The lamp body 1 includes an expanded-out wall 1a provided above the orthogonal conversion gear mechanism 5. The end face 1a1 of the expanded-out wall 1a is positioned on an extended line of the rotational operation bar 4; and as shown by the imaginary lines, the end face 1a1 contacts and supports the side-surface of a screwdriver 7 that is connected to the rotational operation bar 4. In FIG. 8, the reference numeral 1b is a pair of right and left vertical walls provided on the end face 1a1 of the expanded-out wall 1a. The vertical walls support, as a guide that has a U-shaped cross section, the side-surface of the screwdriver 7.
When the rotational operation bar 4 is rotated by the screwdriver 7, the rotational operation bar 4 rotates the aiming screw 3. Since the front end of the aiming screw 3 is screwed to a nut 2a that is fitted in the rear surface of the reflector 2, with the rotation of the aiming screw 3, the nut 2a is moved back and forth by the aiming screw 3; as a result, the reflector 2 is tiltably moved and faces upward and downward.
However, in the above conventional structure, the rotational operation bar 4 and the orthogonal conversion gear mechanism 5 are provided in the aiming mechanism. As a result, the aiming mechanism tends to have a complicated structure and a heavy weight.
As a result, as seen from FIG. 9, the inventors came up with an idea to provide a crown gear 8 on a rearward-extending portion of the aiming screw 3, so that the crown gear 8 is directly rotated by the screwdriver 7. In this structure, the rotational operation bar 4 and the orthogonal conversion gear mechanism 5 are unnecessary, and thus the aiming mechanism is simple in structure and light in weight.
However, when rotating the crown gear 8 by the screwdriver 7, a pressing force P that is applied by the screwdriver 7 causes the aiming screw 3 to swing with respect to the screw insertion hole 1c, and this inhibits a smooth aiming operation. Moreover, when the aiming operation that accompanies the swing of the aiming screw 3 is repeated, looseness occurs between the aiming screw 3 and the screw insertion hole 1c. This would cause an oscillation of the bean position.
After further considerations, the inventors mounted a bracket (not shown) on the rear wall of a lamp body so that the bracket supports the rearward-extending portion of the aiming screw 3. With this structure, the aiming screw 3 does not swing when the crown gear 8 is rotated by the screwdriver 7, and no looseness is generated between the aiming screw 3 and the screw insertion hole 1c. 